Apparatus for monitoring and providing visual representations of the operating conditions of machine tool parameters

ABSTRACT

Apparatus for monitoring and providing visual representations of the operating conditions of machine tool parameters, in particular for program-controlled turning, milling, and drilling machines, which have a machining unit displaceable in a plurality of coordinate axes, in which a work spindle for exchangeable receiving a machining tool and an electric motor for driving the work spindle are mounted. The machine tool includes a control unit and means for monitoring the operating state of the machine tool. The monitoring apparatus has at least one sensor for detecting at least one operating parameter of the machine tool. An evaluating unit is connected to both the sensor and the control unit and processes the measurement values detected by the sensor. An optical display is provided in the direct viewing range of the operator, which viewing range includes the machine operating spindle, tool holder, tool, and workplace. The optical display can display a normal, a critical, and a dangerous operating state of the machine tool in accordance with the data from the evaluating unit.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of prior applicationSer. No. 13/328,575, filed 16 Dec. 2011, ABN, which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to an apparatus for monitoring operating states ofa machine tool such as a program-controlled milling and drillingmachine. Machine tools of this type typically comprise a workplace tableor platform and a machining unit displaceable by a motor in a pluralityof coordinate axes in which a work spindle for exchangeably receiving amachining unit and an electric motor as a rotating drive of the workspindle are mounted, and including a control unit.

DISCUSSION OF THE PRIOR ART

A continuous monitoring of the operating states during the working modeof a machine is essential for recognizing possible disruptive factors atan early stage of their development and for being able to initiatecounter-measures in time. In modern program-controlled machine tools andmachining centers, the set-up of the machine before the machining of aparticular workplace or a series of workpieces is of considerableimportance for achieving smooth work processes under optimizedconditions. So far, the set-up of the machine before the start of thework and the monitoring of its state during operation has exclusivelybeen performed via the control panel, of the control unit which usuallyis on a limitedly moveable stand next to or diagonally in front of themachine and not on or near the same line of sight with the operatingtool and workpiece. Thus, when approaching die machining, the operatorneeds to monitor the indications of the relevant operating parameters onthe control panel and, if possible, at the same time keep an eye on theactual working manner of the tool—in a simulated or also in an actualoperation. The operator has to fulfill similar requirements during themonitoring of the state which possibly extends across long operatingtimes because the continuous observation of the indications on thecontrol panel and the engagement of the work tool on the respectiveworkpiece in the workspace of the machine require significant efforts.

To recognize sources of error as early as possible before they actuallyoccur plays an important role for the continuous operating procedurebecause the occurrence of these errors and thus their serious effects onthe machining of workpieces can be prevented by interventions of theoperator, such as initiating a tool change. The continuous and exactmonitoring of the state of a plurality of complex machines requiresexperienced operators and a high measure of continuous attention to theknown systems now used.

SUMMARY OF EMBODIMENTS OF THE INVENTION

It is a purpose of embodiments of the invention to provide apparatus formonitoring the operating states or conditions of a machine tool to takepressure off the operator and increases the reliable capacity of themachine tool to work properly.

By providing at least one sensor system on a selected component of themachine tool it is possible to continuously monitor a particularoperating parameter on the machine part which is particularly relevantfor this operating parameter. As the operating parameter, the powerconsumption of the electric motor of the work spindle, the vibration atthe output end of the work spindle, the temperature in thermallystressed machine parts, and also the state of the lubricant, may beused, for example. As an evaluating unit is connected to the sensorsystem on the one hand and to the control machine's unit on the otherhand, data from the control unit and data from the sensor system may belinked with each other and processed in order to receive data withrespect to the operating state of the machine. An intensive andfatigue-reducing display is achieved by the fact that an optical displayelement is disposed in the operator's direct viewing range on a machinepart, the display having a device for indicating a normal, a critical,and a dangerous operating state of the machine based on the data outputby the evaluating unit.

The monitoring means of the machine tool, among others, offers theadvantage that an operator may recognize normal and also criticaloperating states of the machine tool at an early time and in a simplemanner by observation, which is primary for the operator, of the opticaldisplay arranged preferably within the working range of the machine. Toemphasize the value of the location of the optical display element, thework spindle, tool holder, and work tool, as well as the workpiece uponwhich the tool is operating, are within the same viewing area as theoptical display element. Thus, a change of the operator's observationangle or position between the display on the control panel and theworking range of the work tool is no longer necessary. The display ofthe respective operating states in different colors promotes thelong-term attention of the operator, in particular in case of a suddenchange of color. Thus, the possibility exists that disturbances anderrors may be recognized by a change of color in the display at an earlytime and before they negatively affect the machining process so thatcountermeasures may be initiated by the operator or also by a controlunit before any malfunctions can have a practical impact. The detectionand display in the run-up to the occurrence of errors lead to improvedoperating procedures and reduced stoppage times of the machine. Theseeffects not only have an impact on the monitoring of the state of anindividual machine but their advantageous effect also shows when asingle operation has to operate and monitor a group of machines.

Although an optical display in, preferably, three traffic light colors,sufficiently fulfills the monitoring function, it may still be suitableto combine the optical display with an acoustic response to thusincrease the attention factor.

According to a suitable design of the present monitoring apparatus, thedisplay contains a plurality of color ranges which are alternatelyactivated, that is, green for normal operation, yellow/orange for lessthan optimal or critical operation, and red for dangerous operation.Here, in a special display element the green field for the normaloperation would typically be substantially larger than the yellow/orangefield for the critical operation, and this in turn would normally belarger than the red field for the dangerous operating state. Aproportional distribution of the available field sizes of green of about60%, yellow/orange of at least 20%, and red of less than 20%, has provenparticularly suitable. The large green field represents a normaloperating state wherein the relative size of the illuminated portion ofthe green field indicates the actual size or strength of the monitoredoperating parameter. Therefore, when the machine is set up the operatormay adjust the machine to a value close to the upper limit of theintensity or size of the green field, that is, at about 60%. Thus, theoperator may, for example, select the forward feed of the tool to be solarge that the power consumption of the electric motor of the workspindle is in the upper range of the green field. The forward feedoptimized in such a manner leads to a corresponding machiningperformance. A similar approach may be performed, for example, bymonitoring vibrations at the tool holder.

The yellow/orange field in the optical display element points out to theoperator that, for example, the power consumption of the spindle motoror the vibrations of the work spindle or the tool are less than optimaland within a limit range, and measures should be initiated shortly toreturn these operating parameters to their normal strengths ormagnitudes. This may be made, for example, by reducing the forward feed,changing the tool, or other measures. What is important is that theefforts and carefulness for monitoring a machine are reduced for anoperator when very diverse set-up works are performed and a plurality ofmachines is monitored, which has a positive effect on the permanentoperation of ail machines.

The optical display is suitably attached to the outside of a side wallof the machining unit as an optical illuminating element so that it willbe in the operator's immediate viewing range, as defined above, if he orshe is watching the operation of a tool on a workpiece in the workingrange of the machine.

Preferably, each field of the display contains a plurality ofluminaires, such as LEDs, which are disposed in a housing capsule with atransparent outer wall and electrically connected to the evaluating unitand the control unit, respectively. In this case it is an advantage ifthe number of the respective luminaires is proportional to the measuredmagnitude or strength of the respective parameter so that the operatoris shown the magnitude and perceived value of the respective relevantoperating parameter by the number of the respectively activatedluminaires and thus by the magnitude of the respective illuminatingfield.

BRIEF DESCRIPTION OF THE DRAWING

In the following, embodiments of the invention will be described indetail by referring to the drawing, wherein:

FIG. 1 is a side view of a universal milling machine comprising a swivelhead in schematic lateral view, with a display apparatus in accordancewith the invention; and

FIG. 2 is a front view of an alternative embodiment of a verticalmilling machine comprising a vertically oriented spindle head, with adisplay apparatus in accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The universal milling machine shown in FIG. 1 comprises rear stand 1 andmachine bed 2 arranged at the lower face thereof, on which workpiecetable 4 can be driven on guiding rails 3 by a motor (not shown) in thedirection of the Y coordinate axis. Horizontal slide 7 is mounted inhorizontal guiding rails 5, 6 at the front of stand 1 so that it can bedisplaced by a motor (not shown) in the direction of the X coordinateaxis. On the front of slide 7 is cross-slide 9 guided in verticalguiding rails 10 so as to be moveable by a motor (not shown) in thedirection of the Z coordinate axis. Head 11 is mounted on the front ofcross-slide 9 so that the head is rotatable about horizontal axis 12.Swivel head 15 is supported on front surface 13 of head 11, inclined by45°. Swivel head 15 can be moved by a motor (not shown) about axis 14which is inclined by 45°. Spindle housing 16 is fixed to one surface ofswivel head 15. Spindle motor 17 (toward the left of housing 16 asshown) and work spindle 18 in front of the motor are arranged in housing16, each of them shown by dashed lines. At the rear end of housing 16 inthe rear area of spindle motor 17, is sensor 20, which continuouslydetects the power consumption of the motor. The motors mentioned hereinare conventional for such machine tools and need not be detailed here.The combination of head 11, swivel head 15, housing 16, spindle 18, andmotor 17 may be referred to as a machining unit.

At the front end area of spindle housing 16 is vibration sensor 21,which detects vibrations which may occur at the tool holder or theclamped tool during operation. Sensors 20 and 21 form at least part of asensor system, which are connected via data lines 22, 23 to evaluatingunit 24 which, in turn, is connected to conventional programmablecontrol unit 25.

Data line 26 leads from control unit 25 to display element 28. Thedisplay element is arranged as a rotationally fixed circular, forexample, illuminating element in a side wall of head 11 at aneconomically favorable position so that it is in the direct viewingrange, which includes the machining unit spindle, tool holder and tool,of an operator standing next to the machine. This display elementcontains a transparent housing capsule in which a plurality ofluminaires in each color field, such as LEDs, is arranged. Furthermore,display element 28 is divided into three color fields, namely a largegreen-colored field occupying about 60% of the illumination surface, amiddle-sized yellow/orange field occupying at least about 20% of theillumination field, and a small red field occupying less than about 20%of the illumination field. Depending on tire measurement values obtainedby sensor system 20, 21 and the operating state determined in evaluatingunit 24, more or fewer lines of LEDs become visible as a green,yellow/orange, or red field. The green field designates the normaloperating state, the yellow/orange field indicates the beginning of acritical operating state, and the red field indicates a dangerousoperating state of the machine tool, each according to the magnitude ofthe detected power consumption and/or vibration, parameters. Thus, whenthe tool and tool holder are operating vibration free, for example, ailthe luminaires in the green field are energized and the green field isfull. As the spindle starts to experience minor vibrations, some of theluminaires in the green field are de-energized, making the green fieldbecome somewhat dim, or visually smaller. That is what is meant by“strength,” “magnitude,” or “size,” as used above in relation to thestatus of the sensed operating parameters.

In order to monitor other states and properties of the machine tool,further operating parameters, such as, for example, the temperatures ofparticularly stressed components or the like, may be detected bycorresponding sensors and included in the monitoring via the evaluatingunit.

The milling and drilling machine schematically shown in a front view inFIG. 2 has base 30 comprising side walls 31, 32 mounted thereon andworkpiece table 33 arranged between the side walls. Transverse traverse35 is mounted in two guiding rails mounted on the top surface of sidewalls 31, 32 so as to be displaceable by a motor (not shown) in thedirection of the Y coordinate axis. Cross-slide 36 is disposed on thefront face of traverse 35 and vertical slide 37 is disposed on the frontof cross-slide 36, both slides being disposed on guiding rails so thatthey can be displaced by a motor or respective motors (not shown). Here,electric linear motors, for example, can serve for driving the slides.Cross-slide 36 is movable in the direction of the X coordinate axis andvertical slide 37 displaceable in the direction of the Z coordinateaxis. This arrangement provides the support for vertical milling head 38in whose housing a work spindle and the drive motor thereof (not shown)are supported.

In order to detect the vibrations occurring at tool holder 39 on the endof the work spindle or the tool clamped therein in machining operations,this embodiment also provides sensor 21 in the front portion of spindlehousing 38, which is connected to evaluating unit 24 via data line 23.In the same manner as in the embodiment of FIG. 1, another sensor 20 isdisposed in the end portion of the spindle drive motor in spindlehousing 38, which sensor detects the power consumption of the electricdrive motor and is connected to evaluating unit 24 via data line 22.Data line 26 leads from evaluating unit 24 to display element 40, whichcorresponds to display element 40 in FIG. 1 as to its function. However,as shown in FIG. 2, display element 28 has an oval or elongated shape.This display element also contains a plurality of colored fields orareas 50 which, depending on the magnitude of the continuously detectedoperating parameter, light up in a specific color and with a specificsize or intensity and thus indicate the respective operating state ofthe parameters of the machine tool to the operator. In this course, thedisplay of only one parameter, for example, of the measured vibrationsor the power consumption of the spindle motor, may be made depending onthe set-up by the operator via keys or switches (not shown) that caneither be provided in the control panel (not shown) of the control unitor in or on the evaluating unit. This element of control is alsoavailable in the FIG. 1 embodiment.

The display, according to the invention embodiments shown, suitablycontains a scaling, for example, in the shape of a division scale for apercentage field size division. A scaling based on a changing number ofactivated illumination elements, that is, LEDs, adapted to the magnitudeand/or perceived value of the measured operating parameter is preferred.

A method for setting up the machine tool for machining a particularworkpiece is characterized in that the operator visually monitors theinterface of tool/workpiece in the working range of the machine, in thesimulated or actual operation, while the set-up works are performed. Inorder to optimize the work procedures and results, the operator may setoperating parameters on the keyboard of the control unit, for example,the spindle forward feed, spindle speed, or the like, so that thecontinuously monitored display is in the upper or more intense colorrange of the green field.

The invention is not limited to the embodiments as shown and describedabove. For example, sensors may be provided for detecting a multitude ofdifferent operating parameters and connected to the evaluating unit oralso directly to the control unit. Depending on the priority of therespective operating parameter, the measurement values of the individualsensors may be displayed separately via the evaluating unit in thedisplay element. There is also the possibility that the evaluating unitlinks the measurement values of the various operating parameters witheach other and supplies data from a combination of these measurementvalues to the display unit. Thus, for example, the support temperaturesof the work spindle, the power consumption of the spindle motor, and thevibrations of the tool holder may be measured individually and displayedindividually as parameters, optionally in a changing sequence. Three ormore parameters may also be processed in the evaluating unit into acommon data set which is displayed and indicates the operating state ofthe machine in a combined assessment of the parameters.

What is claimed is:
 1. A machine tool for machining a workpiece, saidmachine tool comprising: a control unit, a machining unit displaceablein a plurality of coordinate axes, wherein the machining unit includes awork spindle and tool holder for exchangeably receiving tools and amotor for driving the work spindle, two or more sensors for monitoringthe operating condition of at least one operating parameter of saidmachining unit, said two or more sensors including: a vibration sensorwhich detects vibrations occurring on the tool, and a sensorcontinuously detecting the current draw of the motor for driving thework spindle; an evaluating unit connected to said two or more sensorsand to said control unit for processing measurement values detected bysaid two or more sensors and said evaluating unit configured foroutputting output data indicative of the magnitude of the perceivedvalue of the operating condition of said at least one operatingparameter; and an optical display device configured to display magnitudelevels of a normal, a critical, and a dangerous operating condition ofsaid machining unit pursuant to the output data from said evaluatingunit; said optical display device comprising a unitary optical displayelement having a single optically illuminatable surface divided into atleast three dells disposed in an economically favorable position on anoutside wall of said machining tool, said optical display device and themachine work spindle and work tools are in direct viewing range of anoperator of the machine tool, said at least three fields of said unitaryoptical display element of said optical display device being arranged ina transparent housing capsule and having at least three distinctlycolored areas, including a green area occupying at least about 60% ofthe optically illuminatable surface, a yellow/orange area occupying atleast about 20% of the optically illuminatable surface, and a red areaoccupying less than about 20% of the optically illuminatable area, thesize of each said at least three colored areas being constant, and eachof said at least three distinctly colored areas comprising a pluralityof LEDs, and said plurality of LEDs being operatively connected to andbeing responsive to the data output from said evaluating unit toilluminate the LEDs in one said colored area to indicate the magnitudeof the operating condition of the operating parameter being measured,wherein the plurality of LEDs being configured to be activated based onthe magnitude indicated by the data output such that the number ofactivated LEDs among the LEDs is proportional to the magnitude of theoperating condition of the operating parameter being measured.
 2. Themachine tool according to claim 1, wherein said evaluating unit isfunctionally linked to the control unit and determines the respectivestate variable of the monitored operating parameter from the measuredvalues of said two or more sensors and from data of the control unit andactivates the color in the optical display corresponding to the statevariable being monitored.
 3. The machine tool according to claim 1,wherein said optical display is formed as a rotationally fixed, circularlight element.